JP5055291B2 - Mobile communication system, base station apparatus and mobile station apparatus - Google Patents

Description

  The present invention relates to a mobile communication system, a base station apparatus, and a mobile station apparatus that use a cellular radio system.

  At present, in 3GPP (3rd Generation Partnership Project), the W-CDMA system is standardized as a third generation cellular mobile communication system, and services are started sequentially. In addition, HSDPA (High Speed Downlink Packet Access), which further increases the communication speed, has been standardized and the service is about to start.

  On the other hand, in 3GPP, the evolution of third generation wireless access (Evolved Universal Terrestrial Radio Access: hereinafter referred to as “EUTRA”) is being studied. An OFDM (Orthogonal Frequency Division Multiplexing) scheme has been proposed as a downlink of this EUTRA. Further, as an uplink of EUTRA, a single carrier communication method of DFT (Discrete Fourier Transform) -spread OFDM method has been proposed.

  As shown in FIG. 14, the EUTRA uplink is composed of an uplink pilot channel UPiCH (Uplink Pilot Channel), a random access channel RACH (Random Access Channel), and an uplink scheduling channel USCH (Uplink Scheduling Channel). (For example, refer nonpatent literature 1).

  The uplink random access channel RACH of E-UTRA includes an asynchronous random access channel and a synchronous random access channel. Here, the minimum unit of the asynchronous random access channel uses a 1.25 MHz band. Then, for example, as shown in FIG. 15, a plurality of access channels are prepared so that a large number of accesses can be handled.

  The purpose of using the asynchronous random access channel is to synchronize between the mobile station apparatus (hereinafter referred to as “mobile station”) and the base station apparatus (hereinafter referred to as “base station”). In addition, it is also considered to shorten the connection time between the mobile station and the base station by transmitting several bits of information such as a scheduling request for allocating radio resources. On the other hand, the purpose of using the synchronous random access channel is to make a scheduling request (Non-Patent Document 2).

  In asynchronous random access, only the preamble is transmitted for synchronization. This preamble includes a signature which is a signal pattern representing information, and several bits of information can be specified by preparing several tens of signatures. At present, transmission of information of 4 to 6 bits is assumed, and it is assumed that 16 to 64 types of signatures are prepared. The information of 4 to 6 bits includes, for example, the reason for random access, downlink path loss / CQI (Channel Quality Indicator), and random ID. In particular, for reasons of random access, it has been studied to specify the handover, initial access, synchronization maintenance, scheduling request, and the like to improve the access procedure efficiency.

  Here, a configuration example of a signature included in the preamble will be described with reference to FIGS. 16 and 17. FIG. 16 shows a configuration example of a signature when each information is divided into fields and information is designated. In this example, 2 bits are assigned as the reason for random access, 1 bit is assigned as the random ID, and 1 bit is assigned as the CQI. For the reason of random access, for example, “00” is selected when a handover is designated, and “11” is selected when synchronization maintenance is designated. On the other hand, FIG. 17 shows a case where the reason for random access, CQI and random ID are selected flexibly and information is designated. A case where a code of 0 to 15 is assigned to each combination of the reason for random access, CQI, and random ID is shown.

  FIG. 18 is a sequence chart for explaining an example of a conventional random access procedure. FIG. 18 shows a random access procedure when an asynchronous random access channel is used. As shown in FIG. 18, in the conventional random access procedure, first, the mobile station selects a signature based on the reason for random access, downlink path loss / CQI information, random ID, and the like (step (hereinafter referred to as “step”). (Abbreviated as “ST”) 1801). Then, a preamble (random access preamble) including the selected signature is transmitted using an asynchronous random access channel (ST1802).

  When the preamble is received from the mobile station, the base station calculates a synchronization timing shift between the mobile station and the base station from the preamble and performs scheduling to transmit an L2 / L3 (Layer2 / Layer3) message (ST1803). Then, C-RNTI is allocated to a mobile station that requires C-RNTI (Cell-Radio Network Temporary Identity) for random access reasons, and synchronization timing deviation information (synchronization information), scheduling information, signature ID number, and C-RNTI are assigned. Transmit (ST1804).

  When receiving the information from the base station, the mobile station extracts a response from the base station including the transmitted signature ID number (ST1805). Then, the L2 / L3 message is transmitted using the radio resource scheduled by the base station (ST1806). When receiving the L2 / L3 message from the mobile station, the base station returns a response to the mobile station accordingly (ST1807).

  A problem of such random access is that a collision occurs when the same signature and random access channel are selected in a plurality of different mobile stations. When multiple mobile stations select the same signature and transmit using the same radio resource block having the same time and frequency, that is, the same random access channel, a collision occurs in the preamble (ST1802) shown in FIG. To do.

  If the base station cannot detect the preamble (ST1802) due to such a collision, it cannot return a response (ST1804) including synchronization information and the like. In this case, since the mobile station cannot receive a response (ST1804) from the base station, it is necessary to select a signature and a random access channel again after a predetermined time and perform random access.

  On the other hand, when the base station can detect the preamble (ST1802), the base station calculates L2 / L3 message scheduling and synchronization timing deviation, and returns a response (ST1804) to the mobile station. However, a plurality of mobile stations will receive a response (ST1804) from the base station. For this reason, as a result of a plurality of mobile stations transmitting the L2 / L3 message (ST1806) using the scheduled radio resource, a collision occurs in the L2 / L3 message (ST1806).

  If the base station cannot detect the L2 / L3 message (ST1806) due to such a collision, a response (ST1807) cannot be returned. In this case, since the mobile station cannot receive a response (ST1807) from the base station, it is necessary to select a signature and a random access channel again after a predetermined time and perform random access. In this way, when the same signature and random access channel are selected in a plurality of mobile stations, a collision can occur, and in the case where a collision occurs, the maximum number of times until the collision is detected is shown. The time until ST1807 shown in FIG. 18 is required.

  By the way, when a mobile station capable of executing such random access exists at the position shown in FIG. 19, handover is executed. Even when a handover is executed, random access as described above is performed.

  Here, an example of a random access procedure during handover execution will be described. FIG. 20 is a sequence chart for explaining an example of a random access procedure during handover execution. Note that FIG. 20 shows a random access procedure when an asynchronous random access channel is used, as in FIG.

  As shown in FIG. 20, in the random access procedure at the time of executing the handover, first, the mobile station measures the radio wave condition of the adjacent base station as a handover preparation stage (ST2001). Then, the measurement result (measurement report) is transmitted to base station A of the base station that accommodates the mobile station itself (hereinafter referred to as “own base station” as appropriate) (ST2002). When receiving the measurement result from the mobile station, base station A selects the optimum base station from the measurement result (ST2003). Here, it is assumed that base station B is selected as the optimum base station. Then, base station A transmits a handover request command to handover destination base station B (ST2004).

  When receiving the handover request command from base station A, base station B assigns C-RNTI to the mobile station to be handed over (ST2005). Then, a handover request approval command including C-RNTI is notified to base station A as a response to the handover request (ST2006). When receiving the handover request approval command from base station B, base station A transmits a handover command including C-RNTI to the mobile station (ST2007).

  When receiving the handover command from base station A, the mobile station performs downlink synchronization of base station B and confirms the position of the random access channel from the broadcast channel (ST2008). If downlink synchronization is performed, the mobile station selects one signature from signatures whose reason for random access is handover (ST2009). Then, a preamble (random access preamble) including the selected signature is transmitted to base station B through a random access channel (ST2010).

  When the signature is detected from the preamble received from the mobile station, the base station B calculates a synchronization timing shift and performs uplink scheduling for transmitting a handover complete message from the mobile station (ST2011). Then, synchronization timing shift information (synchronization information), scheduling information, and signature ID number are transmitted (ST2012). When the handover is a reason for random access, the C-RNTI is not transmitted because the C-RNTI is notified in advance.

When receiving the information addressed to base station B from base station B, the mobile station corrects the synchronization timing shift based on the synchronization timing shift information (synchronization information) (ST2013). Then, a handover completion message is transmitted using the scheduled radio resource (ST2014). When receiving the handover complete message from the mobile station, base station B returns a response to the mobile station accordingly (ST2015).
R1-050850 “Physical Channel and Multiplexing in Evolved UTRA Uplink”, 3GPP TSG RAN WG1 Meeting # 42 London, UK, August 29-September 2, 2005 3GPP TR (Technical Report) 25.814, V7.0.0 (2006-06), Physical layer aspects for evolved Universal Terrestrial Radio Access (UTRA)

  In random access due to such a handover, communication is interrupted when a collision occurs with another mobile station, so it is desirable that no collision occurs. However, in a mobile communication system in which a mobile station randomly selects a signature or a random access channel, the actual situation is that the collision probability cannot be completely eliminated. In order to prevent collisions, when using an uplink scheduling channel, uplink synchronization between the mobile station and the base station is not established, so data from the mobile station must be received by the base station. I can't.

  Also, when a base station other than the handover destination base station responds to random access from the mobile station (in this case, for example, when base station-A and base station-C shown in FIG. 19 respond) ), And there is also a problem that an extra downlink radio resource is allocated.

  Furthermore, when the paging message notified by the base station to call the mobile station is received, the mobile station is expected to perform random access as a paging response. When a collision occurs during the random access as such a paging response, there is a problem that not only the connection time is lengthened but also the communication efficiency is deteriorated.

  The present invention has been made in view of such problems, and occurs when a mobile station apparatus performs random access in response to an instruction from the base station apparatus, such as a handover or a paging response, during random access. It is an object of the present invention to provide a mobile communication system, a base station apparatus, and a mobile station apparatus that can prevent a collision.

  (1) In order to achieve the above object, the present invention has taken the following measures. That is, the mobile communication system according to the present invention is a mobile communication system in which a mobile station apparatus uses any one of a predetermined signature group with a base station apparatus at the time of random access. And a signature group managed by the base station apparatus and a signature group managed by the mobile station apparatus.

  Thus, since the signature group managed by the base station apparatus is provided in the signature group used by the mobile station apparatus during random access, it is possible to perform random access under the leadership of the base station apparatus. When the mobile station apparatus performs random access in response to an instruction from the base station apparatus such as an over or paging response, it is possible to prevent a collision that occurs during random access.

  (2) The mobile communication system according to the present invention is characterized in that a signature group managed by the base station apparatus includes a signature selected by the base station apparatus, which is associated with a specific reason for random access. Yes.

  In this way, since a signature associated with a specific random access reason is selected by the base station device, a different signature can be assigned to each mobile station device, and the same signature can be assigned during random access by the mobile station device. It is possible to prevent a collision that occurs due to the selection of.

  (3) The mobile communication system of the present invention is characterized in that the signature group managed by the base station apparatus includes a signature preferentially selected by an adjacent base station apparatus.

  As described above, since the signature group managed by the base station apparatus includes the signature preferentially selected by the adjacent base station apparatus, the signature selected with the adjacent base station apparatus is adjusted. Therefore, it is possible to reduce the collision at the time of random access that may occur between adjacent base station apparatuses.

  (4) The mobile communication system of the present invention is characterized in that the base station apparatus shares information on signatures selected from each other with adjacent base station apparatuses.

  As described above, since the information of the signatures selected from each other is shared with the adjacent base station apparatus, it is possible to adjust the signature to be selected with the adjacent base station apparatus. It becomes possible to reduce the collision at the time of random access that may occur with the base station apparatus.

  (5) For example, the mobile communication system of the present invention is characterized in that the signature group managed by the base station apparatus includes a signature associated with a handover as the reason for the specific random access.

  Thus, since the signature group managed by the base station apparatus includes a signature associated with handover as the reason for the specific random access, communication is interrupted due to collision in random access performed at the time of handover. It becomes possible to prevent the situation.

  (6) In particular, the mobile communication system of the present invention is characterized in that the signature selected by the base station apparatus is included in a handover message for starting execution of handover and transmitted to the mobile station apparatus.

  Thus, since the signature selected by the base station apparatus is included in the handover message and transmitted to the mobile station apparatus, the signature selected by the base station apparatus is transmitted to the mobile station apparatus using the existing signal. Is possible.

  (7) In the mobile communication system of the present invention, the signature group managed by the base station device includes a signature associated with a response at the time of paging reception as the reason for the specific random access. .

  As described above, since the signature group managed by the base station apparatus includes a signature associated with a response at the time of paging reception as a specific random access reason, in random access at the time of paging response, due to collision It is possible to prevent a situation in which the connection time is long.

  (8) Further, the mobile communication system of the present invention is characterized in that the signature selected by the base station is included in a paging message for calling the mobile station apparatus and transmitted to the mobile station apparatus.

  Thus, since the signature selected by the base station apparatus is included in the paging message and transmitted to the mobile station apparatus, the signature selected by the base station apparatus can be transmitted to the mobile station apparatus using an existing signal. It becomes possible.

  (9) The mobile communication system of the present invention includes a signature group managed by the base station device according to a communication status of the base station device and the mobile station device communicating with the base station device, and the mobile It is characterized in that the ratio with the signature group managed by the station apparatus is changed.

  As described above, since the ratio between the signature group managed by the base station apparatus and the signature group managed by the mobile station apparatus is changed according to the current communication status, both optimal according to the current communication status The ratio of signature groups can be determined, and it is possible to efficiently prevent collisions during random access.

  (10) Further, the mobile communication system of the present invention includes the signature group managed by the base station apparatus and the content related to the signature group managed by the mobile station apparatus in broadcast information and transmits the broadcast information to the mobile station apparatus. It is characterized by that.

  In this way, since the contents related to the signature group managed by the base station apparatus and the signature group managed by the mobile station apparatus are included in the broadcast information and transmitted to the mobile station apparatus, the base station can be utilized by utilizing the existing signal. It is possible to transmit the contents related to the signature group managed by both the apparatus and the mobile station apparatus to the mobile station apparatus.

  (11) Further, the mobile communication system of the present invention is characterized in that a signature is selected by the base station apparatus and a frequency band position and / or a time position for random access are selected.

  In this way, since the base station apparatus selects not only the signature but also the frequency band position and / or time position of random access, the frequency band position and / or time position of the random access channel can be selected at the time of random access. It is possible to reduce the probability of collision at.

  (12) A base station apparatus according to the present invention is a base station apparatus connected to a mobile station apparatus that uses one of the signatures of a predetermined signature group at the time of random access. A signature selection unit that selects a signature associated with the reason for random access, and a signature management unit that manages the signature selected by the signature selection unit.

  In this way, the signature selection unit selects a signature that is associated with a specific reason for random access from among the signature group used during random access, so that a different signature can be assigned to each mobile station device. Thus, it is possible to prevent a collision that occurs due to the same signature being selected during random access by the mobile station apparatus.

  (13) In the base station apparatus of the present invention, the signature associated with the specific random access reason includes a signature preferentially selected by an adjacent base station apparatus, and the signature selection unit Signatures other than signatures preferentially selected by the base station apparatus are preferentially selected.

  As described above, since the signature selection unit preferentially selects a signature other than the signature preferentially selected by the adjacent base station apparatus, the signature selected with the adjacent base station apparatus is adjusted. Therefore, it is possible to reduce the collision at the time of random access that may occur between adjacent base station apparatuses.

  (14) In the base station apparatus of the present invention, the signature associated with the specific random access reason includes a signature preferentially selected by an adjacent base station apparatus, and the signature management unit includes It is characterized in that information on signatures selected from each other is shared with adjacent base station apparatuses.

  As described above, since the signature management unit shares the information of the signatures selected with each other between the adjacent base station apparatuses, it is possible to adjust the signature selected with the adjacent base station apparatus. Therefore, it is possible to reduce the collision at the time of random access that may occur between the adjacent base station apparatuses.

  (15) For example, the base station apparatus of the present invention is characterized in that the signature selection unit selects a signature associated with a handover as the reason for the specific random access.

  As described above, since the signature associated with the handover is selected by the signature selection unit, it is possible to prevent a situation in which communication is interrupted due to a collision in random access performed at the time of handover.

  (16) Particularly, the base station apparatus of the present invention is characterized in that the signature selected by the signature selection unit is included in a handover message for starting execution of handover and transmitted to the mobile station apparatus.

  Thus, since the selected signature is included in the handover message and transmitted to the mobile station apparatus, the signature selected by the base station apparatus can be transmitted to the mobile station apparatus using the existing signal. .

  (17) Further, the base station apparatus of the present invention is characterized in that the signature selection unit selects a signature associated with a response at the time of paging reception as the reason for the specific random access.

  In this way, the signature selection unit selects a signature to which a response at the time of paging reception is associated, so that it is possible to prevent a situation in which the connection time is prolonged due to collision in random access at the time of paging response. It becomes.

  (18) In particular, the base station apparatus of the present invention is characterized in that the signature selected by the signature selection unit is included in a paging message for calling the mobile station apparatus and transmitted to the mobile station apparatus.

  As described above, since the selected signature is included in the paging message and transmitted to the mobile station apparatus, it is possible to transmit the signature selected by the base station apparatus to the mobile station apparatus using an existing signal.

  (19) The base station apparatus of the present invention is characterized in that the number of signatures that can be selected by the signature selection unit is increased / decreased in accordance with the communication status with the mobile station apparatus that is in communication.

  In this way, the number of signatures that can be selected by the signature selection unit is increased / decreased according to the communication status with the mobile station device in communication, so the optimal number of signatures can be selected according to the current communication status. It is possible to efficiently prevent collision at random access.

  (20) In addition, the base station apparatus of the present invention includes the result of increasing or decreasing the signature that can be selected by the signature selection unit in the broadcast information according to the communication status with the mobile station apparatus that is communicating. It transmits to a mobile station apparatus.

  In this way, since the result of increasing or decreasing the signature that can be selected by the signature selecting unit is included in the broadcast information and transmitted to the mobile station apparatus, the signature increasing and decreasing result that can be selected by the signature selecting unit using the existing signal is displayed. It is possible to transmit to the mobile station device.

  (21) In the base station apparatus of the present invention, the signature selection unit selects a signature associated with the reason for the specific random access, a frequency band position and / or a time position of the random access, and the signature management The unit manages the signature selected by the signature selection unit and the frequency band position and / or time position of random access.

  In this way, not only the signature associated with a specific random access reason but also the frequency band position and / or time position of random access are selected by the signature selection unit and managed by the signature management unit. By selecting the frequency band position and / or time position of the access channel, it is possible to reduce the probability of collision during random access.

  (22) A mobile station apparatus of the present invention is a mobile station apparatus that is connected to a base station apparatus and transmits a signature of a predetermined signature group at the time of random access, and is transmitted from the base station apparatus A receiving unit that receives a signal; a control data extracting unit that extracts a signature from the signal; and a transmitting unit that transmits a preamble corresponding to the extracted signature to the base station device or another base station device. It is characterized by providing.

  Thus, since the signal transmitted from the base station apparatus is received, the signature is extracted from the signal, and the preamble corresponding to the extracted signature is transmitted to the base station apparatus or another base station apparatus. Random access can be performed at the initiative of the base station apparatus. As a result, when the mobile station apparatus performs random access in response to an instruction from the base station apparatus such as a handover or paging response, it is possible to prevent a collision that occurs during random access. Also, the base station device refers to the preamble received from the mobile station device, and if it is not the signature assigned by itself, the base station device does not respond to the mobile station device in the downlink, Thus, the use of downlink radio resources is not wasted.

  According to the present invention, since the signature group managed by the base station apparatus is provided in the signature group used by the mobile station apparatus during random access, it becomes possible to perform random access under the initiative of the base station apparatus. When the mobile station apparatus performs random access in response to an instruction from the base station apparatus such as a handover or paging response, it is possible to prevent a collision that occurs during random access.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. A mobile communication system according to an embodiment of the present invention (hereinafter referred to as “communication system” as appropriate) has been conventionally performed by a mobile station apparatus (hereinafter referred to as “mobile station”) regardless of the purpose of random access. Signature management (selection) can be partially performed by a base station apparatus (hereinafter referred to as “base station”) depending on the reason for random access.

  That is, in the communication system according to the present embodiment, the signature managed by the base station (hereinafter referred to as “base station management signature” as appropriate) and the signature managed by the mobile station according to the purpose of random access. (Hereinafter referred to as “mobile station management signature” as appropriate). In other words, the base station management signature is a signature selectable in the base station, and the mobile station management signature is in other words a signature selectable in the mobile station.

(First embodiment)
FIG. 1 is a diagram for explaining a signature setting example in the communication system according to the first embodiment of the present invention. In the communication system according to the first embodiment, as shown in FIG. 1, signature ID numbers (hereinafter referred to as “signature numbers”) 1 to 24 are assigned as base station management signatures, and mobile station management signatures are assigned. Signature numbers 25 to 64 are assigned. In particular, in the communication system according to the first embodiment, handover is set for the signature numbers 1 to 24 as the purpose of use, and a scheduling request, initial value is set as the purpose of use for the signature numbers 25 to 64. Access and maintenance (synchronization) are set.

  Here, the configuration of the base station and mobile station included in the communication system according to the first embodiment in which the signature is set in this way will be described. FIG. 2 is a block diagram illustrating an example of a configuration of a base station included in the communication system according to the first embodiment. FIG. 3 is a block diagram illustrating an example of a configuration of a mobile station included in the communication system according to the first embodiment.

  As shown in FIG. 2, the base station 100 includes a data control unit 101, an OFDM modulation unit 102, a scheduling unit 103, a radio unit 104, a channel estimation unit 105, a DFT-Spread-OFDM demodulation unit (DFT-S-OFDM demodulation unit). ) 106, a control data extraction unit 107, a preamble detection unit 108, a signature selection unit 109, and a signature management unit 110.

  The data control unit 101 receives input of control data and user data, and transmits control data according to an instruction from the scheduling unit 103 in the downlink common control channel, the downlink synchronization channel, the downlink pilot channel, and the downlink shared control signaling channel. On the other hand, transmission data (user data) for each mobile station is mapped to a shared data channel. The OFDM modulation unit 102 performs OFDM signal processing such as data modulation, serial / parallel conversion of input signals, IFFT (Inverse Fast Fourier Transform) conversion, CP (Cyclic Prefix) insertion, and filtering, and generates an OFDM signal.

  The scheduling unit 103 includes a DL scheduling unit 103a that performs downlink scheduling and a UL scheduling unit 103b that performs uplink scheduling. The DL scheduling section 103a performs scheduling for mapping user data to each downlink channel from CQI information notified from the mobile station and data information of each user notified from the higher layer. The UL scheduling section 103b performs scheduling for mapping user data to each uplink channel from the uplink radio channel estimation result from the channel estimation section 105 and the resource allocation request from the mobile station.

  The radio unit 104 up-converts OFDM-modulated data to a radio frequency and transmits it to the mobile station. Radio section 104 receives uplink data from the mobile station, down-converts it to a baseband signal, and receives the received data to channel estimation section 105, DFT-S-OFDM demodulation section 106, and preamble detection section 108. hand over.

  Channel estimation section 105 estimates radio channel characteristics from uplink pilot channel UPiCH, and passes the estimation result to DFT-S-OFDM demodulation section 106. In addition, the radio channel estimation result is passed to the scheduling unit 103 in order to perform uplink scheduling. The uplink communication scheme is assumed to be a single carrier scheme such as DFT-S-OFDM, but may be a multicarrier scheme such as the OFDM scheme.

  The DFT-S-OFDM demodulation unit 106 demodulates the received data passed from the radio unit 104 according to the radio channel estimation result from the channel estimation unit 105. The control data extraction unit 107 separates the received data into user data (uplink shared data channel USDCH) and control data (uplink shared control signaling channel USCSCH). Among the separated control data, downlink CQI information is passed to the scheduling unit 103, and other control data and user data are passed to the upper layer.

  The preamble detection unit 108 detects the preamble, calculates the synchronization timing deviation amount, and reports the signature number and the synchronization timing deviation amount. If the signature number is a base station management signature number, which will be described later, the signature management unit 110 confirms whether the signature is used by the base station 100. As a result of the confirmation, if the signature is used by the base station 100, the signature number and the synchronization timing deviation amount are reported to the upper layer. On the other hand, when the signature is not used by the base station 100, the signature number and the synchronization timing shift amount are not reported to the upper layer.

  The signature selection unit 109 selects a signature according to an instruction from the upper layer and notifies the upper layer and the signature management unit 110 of the signature. When selecting a signature, the signature number used with respect to the signature management unit 110 is confirmed, and the signature number is selected from the ones excluding the used signature.

  Signature management section 110 stores the signature ID number selected by signature selection section 109 and deletes the base station management signature detected by preamble detection section 108 from the stored contents.

  On the other hand, as shown in FIG. 3, the mobile station 200 includes a data control unit 201, a DFT-S-OFDM modulation unit 202, a scheduling unit 203, a signature selection unit 204, a preamble generation unit 205, a synchronization correction unit 206, and a radio unit 207. , A channel estimation unit 208, an OFDM demodulation unit 209, and a control data extraction unit 210.

  The data control unit 201 receives input of user data and control data, and maps these data to an uplink scheduling channel according to an instruction from the scheduling unit 203. The DFT-S-OFDM modulation unit 202 performs data modulation, performs DFT-S-OFDM signal processing such as DFT conversion, subcarrier mapping, IFFT conversion, CP (Cyclic Prefix) insertion, and filtering, and performs a DFT-Spread-OFDM signal. Is generated. The uplink communication scheme is assumed to be a single carrier scheme such as DFT-Spread OFDM, but may be a multicarrier scheme such as the OFDM scheme.

  The scheduling unit 203 performs scheduling for mapping user data to each uplink channel from CQI information notified from a channel estimation unit 208 (to be described later) or scheduling information notified from an upper layer.

  The signature selection unit 204 selects a signature number to be used for random access in accordance with an instruction from an upper layer. The purpose of random access is notified as an instruction from the upper layer. When the notified purpose is the purpose of base station management such as handover or paging, the signature number indicated by the higher layer is selected. On the other hand, if it is the purpose of mobile station management, the signature is randomly selected from the signatures classified according to the purpose from the signatures of mobile station management according to the purpose, and the selected signature number is assigned to the preamble generation unit 205. To pass.

  The preamble generation unit 205 generates a preamble with the signature number selected by the signature selection unit 204 and passes it to the DFT-S-OFDM modulation unit 202. The synchronization correction unit 206 determines the transmission timing from the synchronization information passed from the control data extraction unit 210 described later, and passes the data modulated to match the transmission timing to the radio unit 207. The radio unit 207 sets the radio frequency, up-converts the modulated data to the radio frequency, and transmits the radio data to the base station 100. Radio section 207 receives downlink data from base station 100, down-converts it to a baseband signal, and passes the received data to OFDM demodulation section 209.

  Channel estimation section 208 estimates the radio channel characteristics from the downlink pilot channel and passes the estimation result to OFDM demodulation section 209. In addition, in order to notify the base station 100 of the wireless channel estimation result, the base station 100 converts it to CQI information and passes the CQI information to the scheduling unit 203.

  The OFDM demodulator 209 demodulates the received data passed from the radio unit 207 according to the radio channel estimation result of the channel estimation unit 208.

  The control data extraction unit 210 separates received data into user data and control data. Scheduling information in the separated control data is passed to the scheduling unit 203, uplink synchronization information is passed to the synchronization correction unit 206, and other control data and user data are passed to the upper layer.

  Next, an example of a random access procedure at the time of executing handover in the communication system having the above configuration will be described. FIG. 4 is a sequence chart for explaining an example of a random access procedure at the time of executing handover in the communication system according to the first embodiment. Here, it is assumed that mobile station 200 is currently housed in base station 100A (hereinafter referred to as “base station A” as appropriate).

  As shown in FIG. 4, in the random access procedure at the time of executing handover in the communication system according to the first embodiment, the mobile station 200 first determines the radio wave conditions of adjacent base stations as a handover preparation stage. Measure (ST401). Then, the measurement result (measurement report) is transmitted to base station A, which is its own base station (ST402). When receiving the measurement result from the mobile station, base station A selects the optimum base station from the measurement result (ST403). Here, it is assumed that base station 100B (hereinafter referred to as “base station B” as appropriate) is selected as the optimum base station. Then, base station A transmits a handover request command to handover destination base station B (ST404).

  When receiving the handover request command from base station A, base station B selects one signature from the base station management signatures (ST405). Here, it is assumed that the signature with signature number 1 is selected. In this case, the base station B selects a signature from the base station management signatures excluding the signature used in the base station B in order to avoid random access collision. Then, after allocating C-RNTI to mobile station 200 to be handed over, handover request approval command including signature number and C-RNTI is notified to base station A as a response to the handover request command (ST406).

  When receiving the handover request approval command from base station B, base station A transmits a handover command (handover message) including a signature number and C-RNTI to mobile station 200 (ST407). When receiving the handover command from base station A, mobile station 200 performs downlink synchronization of base station B and confirms the position of the random access channel from the broadcast channel (ST408). If downlink synchronization is performed, the mobile station 200 uses the random access channel to transmit the preamble (random access preamble) including the signature of the signature number added to the handover command, that is, the signature of the signature number 1. Transmit to base station B (ST409).

  When the signature is detected from the preamble received from the mobile station 200, the base station B determines whether it is the signature assigned by itself (ST410). Here, the signature number 1 signature is received, and since the signature number 1 signature is a signature assigned by itself, the base station B calculates the amount of synchronization timing deviation and transmits a handover complete message. Scheduling is performed (ST411). Then, synchronization timing shift information (synchronization information), scheduling information, and C-RNTI are transmitted (ST412). In this case, since C-RNTI is notified in advance, the mobile station 200 does not need a signature number as identification information to be confirmed as data addressed to the mobile station 200, and may be C-RNTI.

  If it is determined in ST410 that the signature received from mobile station 200 is not the signature assigned by itself, no response is made to mobile station 200 and this is left as it is (ST413).

  When receiving the information addressed to the own station from the base station B, the mobile station 200 corrects the synchronization timing deviation based on the synchronization timing deviation information (synchronization information) (ST414). Then, a handover complete message is transmitted using the scheduled radio resource (ST415). When receiving the handover complete message from the mobile station 200, the base station B returns a response to the mobile station 200 accordingly (ST416).

  Thus, in the communication system according to the first embodiment, the signature group (base station management signature) managed by the base station 100 is provided in the signature group used by the mobile station 200 during random access. Since random access can be performed under the initiative of the base station 100, when the mobile station 200 performs random access according to an instruction from the base station 100, it is possible to prevent a collision that occurs during random access. It becomes.

  In the communication system according to the first embodiment, the base station management signature includes a signature selected by the base station 100 in association with a specific reason for random access such as handover. Since the base station 100 selects a signature associated with a specific random access reason as described above, it is possible to assign a different signature to each mobile station 200, and the same signature is used when the mobile station 200 performs random access. It is possible to prevent a collision that occurs due to the selection of.

  In particular, in the communication system according to the first embodiment, since the base station management signature includes a signature associated with handover as the reason for random access, there is a collision in random access performed at the time of handover. The situation that occurs can be prevented. As a result, it is possible to prevent a situation where communication is interrupted due to a collision. In addition, when the base station A which is its own base station and an adjacent base station (not shown) receive a handover signature from the mobile station 200, if the signature is not assigned by the local station, the downlink Thus, since no response is returned to the mobile station 200, downlink radio resources are not wasted.

  In the communication system according to the first embodiment, since the signature selected by the base station 100 is included in the handover message and transmitted to the mobile station 200, the base station 100 selects using the existing signal. This signature can be transmitted to the mobile station 200.

(Second Embodiment)
In the communication system according to the first embodiment, the base station 100 selects a signature and manages information on the signature used in the base station 100, thereby allowing the base station 100 in random access at the time of handover. Prevent collisions inside. However, in the mobile station 200 accommodated in an adjacent base station, a handover occurs almost simultaneously, and a collision can occur when the same signature is selected. In the communication system according to the second embodiment, a random number at the time of handover that can occur with an adjacent base station by adjusting the signature number selected with such an adjacent base station. It reduces access collisions.

  In addition, about the structure of the base station 100 and the mobile station 200 which comprise the communication system which concerns on 2nd Embodiment, since it has the same structure as 1st Embodiment, the description is abbreviate | omitted. The signature in the communication system according to the second embodiment is different from the communication system according to the first embodiment in that a signature range used preferentially by each base station is provided in a base station management signature. .

  FIG. 5 is a diagram for explaining a signature setting example in the communication system according to the second embodiment of the present invention. In the communication system according to the second embodiment, as shown in FIG. 5, each base station (in this case, base station A to base station C) is assigned to signature numbers 1 to 24 assigned as base station management signatures. Has a preferential range of use. Specifically, a range used preferentially by the base station A (hereinafter referred to as “base station A preferential use range” as appropriate) is set as signature numbers 1 to 8, and a range preferentially used by the base station B (hereinafter, referred to as “base station A preferential use range”). As appropriate, “base station B preferential use range” is designated as signature numbers 9-16, and a range preferentially used by base station C (hereinafter referred to as “base station C preferential use range” as appropriate) is designated as signature numbers 17-24. Yes.

  In this case, the base station A assigns signatures to mobile stations that are handed over in order from the signature number 1. Similarly, base station B assigns signatures to mobile stations that are handed over in order from signature number 9 and base station C from signature number 17 in order. Then, when all the signatures in the range that is preferentially used in each base station are assigned to the mobile station, the signature is selected from the lower number in the range that is preferentially used by other base stations. For example, when the base station A assigns all the signatures from the signature numbers 1 to 8 to the mobile station, the lowest signature number 16 in the base station B preferential use range or the base station C preferential use range Signatures are selected in order from the lowest signature number 24.

  As described above, in the communication system according to the second embodiment, the signature number range to be used preferentially with the adjacent base station is determined in advance and the signature selection is adjusted. Thus, it is possible to reduce collisions in random access during handover that may occur between adjacent base stations.

(Third embodiment)
In the communication system according to the second embodiment, a signature preferentially used with an adjacent base station in order to reduce collision in random access at the time of handover that may occur with the adjacent base station. A range of numbers is determined in advance, and signature selection is adjusted. On the other hand, in the communication system according to the third embodiment, by sharing the signature information to be used with the adjacent base station, randomness at the time of handover that can occur with the adjacent base station is possible. It reduces access collisions.

  In addition, about the structure of the base station 100 and the mobile station 200 which comprise the communication system which concerns on 3rd Embodiment, since it has the same structure as 1st Embodiment, the description is abbreviate | omitted. Also, the signatures in the communication system according to the third embodiment are assigned with signature numbers 1 to 24 as base station management signatures as in the communication system according to the first embodiment, and the signatures as mobile station management signatures. Assume that numbers 25 to 64 are assigned.

  Hereinafter, an example of a random access procedure at the time of executing handover in the communication system according to the third embodiment will be described. FIG. 6 is a sequence chart for explaining an example of a random access procedure at the time of executing handover in the communication system according to the third embodiment of the present invention. Here, it is assumed that the mobile station 200 is currently accommodated in the base station A. The base station A is assumed to be adjacent to a base station B and a base station 100C (hereinafter referred to as “base station C” as appropriate) (for example, see FIG. 19).

  As shown in FIG. 6, in the random access procedure at the time of executing handover in the communication system according to the third embodiment, first, the mobile station 200 determines the radio wave conditions of adjacent base stations as a handover preparation stage. Measure (ST601). Then, the measurement result (measurement report) is transmitted to base station A, which is its own base station (ST602). When receiving the measurement result from the mobile station, base station A selects the optimum base station from the measurement result (ST603). Here, it is assumed that base station B is selected as the optimum base station. Then, the base station A transmits a handover request command to the handover destination base station B (ST604).

  When receiving the handover request command from the base station A, the base station B selects one signature from the base station management signatures (ST605). Here, it is assumed that signature number 1 is selected. In this case, in order to avoid random access collision, the base station B includes a base station management signature excluding a signature used in the base station B and a signature used in another base station. Select a signature from. Then, after assigning C-RNTI to mobile station 200 to be handed over, handover request approval command including signature number and C-RNTI is notified to base station A as a response to the handover request command (ST606).

  When receiving the handover request approval command from base station B, base station A transmits a handover command including a signature number and C-RNTI to mobile station 200 (ST607). Also, base station A transmits a handover notification command for notifying that base station C uses signature number 1 between base station A and base station B to base station C (ST608). When the handover notification command arrives from the base station A, the base station C receives this (ST609). It is registered between the base station A and the base station B that the signature number 1 is used.

  When receiving the handover command from base station A, mobile station 200 synchronizes the downlink of base station B and confirms the position of the random access channel from the broadcast channel (ST610). If downlink synchronization is performed, the mobile station 200 uses the random access channel to transmit the preamble (random access preamble) including the signature of the signature number added to the handover command, that is, the signature of the signature number 1. Access to the base station B (ST611).

  When the signature is detected from the preamble received from the mobile station 200, the base station B determines whether it is the signature assigned by itself (ST612). Here, the signature number 1 signature is received, and since the signature number 1 signature is a signature assigned by itself, the base station B calculates the amount of synchronization timing deviation and transmits a handover complete message. Scheduling is performed (ST613). Then, synchronization timing shift information (synchronization information), scheduling information, and C-RNTI are transmitted (ST614). In this case, since C-RNTI is notified in advance, the mobile station 200 does not need a signature number as identification information to be confirmed as data addressed to the mobile station 200, and may be C-RNTI.

  If it is determined in ST612 that the signature received from mobile station 200 is not the signature assigned by itself, the mobile station 200 is not responded and left as it is (ST615).

  When receiving the information addressed to base station B from base station B, mobile station 200 corrects the synchronization timing shift based on the synchronization timing shift information (synchronization information) (ST616). Then, a handover completion message is transmitted using the scheduled radio resource (ST617). When receiving the handover complete message from the mobile station 200, the base station B returns a response to the mobile station 200 accordingly (ST618).

  As described above, in the communication system according to the third embodiment, the signature information to be used is shared with the adjacent base station, and the selection of the signature is adjusted. It is possible to reduce collisions in random access during handover that may occur between the two.

  Note that, in the communication system according to the third embodiment, a case where the base station A that has transmitted the handover request command transmits a handover notification command to the adjacent base station C as shown in ST608 illustrated in FIG. 6 is illustrated. ing. However, the base station that transmits the handover notification command is not limited to the base station A that has transmitted the handover request command, but may be the base station B that has received the handover request command. Even in such a change, it is possible to obtain the same effect as the case described above.

  Further, in the communication systems according to the first to third embodiments, a case where a signature is selected in the base station 100 and notified to the mobile station 200 by a handover command (handover message) is shown. However, the information that can be notified by the handover command is not limited to this, and can be changed as appropriate. For example, not only the signature but also the frequency band position of the random access channel may be selected and notified to the mobile station by a handover message. In this case, since the probability of collision at the time of random access can be reduced by selecting the frequency band position of the random access channel, it is possible to cope with handovers occurring simultaneously in more mobile stations 200. It becomes possible.

  Further, in addition to the frequency band position of the random access channel, a time position may be selected and notified to the mobile station 200 by a handover message. In this case, since it is possible to further reduce the probability of collision at the time of random access, it is possible to cope with handovers that occur simultaneously in more mobile stations 200. However, when signature sets having different ranges are assigned to each base station 100, in other words, when the signatures that can be used differ for each base station 100, it is necessary to notify and adjust the signatures between the base stations 100. Rather, it is only necessary to perform management within the base station 100.

(Fourth embodiment)
In the communication systems according to the first to third embodiments, a case where a handover is set as a purpose of use for a signature of base station management is shown. However, the usage purpose set in the base station management signature is not limited to this, and can be changed as appropriate. In the communication system according to the fourth embodiment, not only a handover but also a paging response is set as a purpose of use for a base station management signature.

  In addition, about the structure of the base station 100 and the mobile station 200 which comprise the communication system which concerns on 4th Embodiment, since it has the same structure as 1st Embodiment, the description is abbreviate | omitted. The signature in the communication system according to the fourth embodiment is different from the communication system according to the first embodiment in that a handover and a paging response are set for the purpose of use in the signature of the base station management. .

  FIG. 7 is a diagram for explaining a signature setting example in the communication system according to the fourth embodiment of the present invention. In the communication system according to the fourth embodiment, as shown in FIG. 7, signature numbers 1 to 32 are assigned as base station management signatures, and signature numbers 33 to 64 are assigned as mobile station management signatures. Assigned. Among base station management signatures, signature numbers 1 to 16 have a handover set as the purpose of use, and signature numbers 17 to 32 have a paging response set as the purpose of use. Yes.

  Hereinafter, an example of a random access procedure at the time of paging reception in the communication system according to the fourth embodiment will be described. FIG. 8 is a sequence chart for explaining an example of a random access procedure at the time of paging reception in the communication system according to the fourth embodiment.

  As shown in FIG. 8, in the random access procedure at the time of paging reception in the communication system according to the fourth embodiment, first, paging information is transmitted from the access gateway AGW (Access Gateway) to the base station 100. (ST801).

  When receiving the paging information from access gateway AGW, base station 100 selects one signature from the signatures for paging response among the signatures managed by the base station (ST802). Here, it is assumed that the signature number 17 is selected. In this case, the base station 100 selects a signature from base station management signatures excluding the paging response signature used in the base station 100 in order to avoid random access collision. Then, the selected signature number is added to the paging message and transmitted to mobile station 200 (ST803).

  When receiving the paging message from the base station 100, the mobile station 200 uses the random access channel to base the preamble (random access preamble) including the signature of the signature number added to the paging message, that is, the signature of the signature number 17 Transmit to station 100 (ST804). When the signature is detected from the preamble received from mobile station 200, base station 100 determines whether it is the signature assigned by itself (ST805). Here, the signature number 17 is received, and since the signature number 17 is the signature assigned by itself, the base station 100 calculates the amount of synchronization timing deviation and transmits the L2 / L3 message. Scheduling is performed (ST806). Further, C-RNTI is selected, and synchronization timing shift information (synchronization information), scheduling information, C-RNTI, and signature number are transmitted to mobile station 200 (ST807).

  If it is determined in ST805 that the signature received from mobile station 200 is not the signature assigned by itself, no response is made to mobile station 200 and this is left as it is (ST808).

  When receiving information addressed to the mobile station from base station 100, mobile station 200 transmits an L2 / L3 message using the scheduled radio resources (ST809). When receiving the L2 / L3 message from mobile station 200, base station 100 returns a response to mobile station 200 accordingly (ST810).

  As described above, in the communication system according to the fourth embodiment, since the signature of the base station management includes the signature associated with the response at the time of paging reception as the reason for random access, in the random access at the time of paging response A situation in which a collision occurs can be prevented. As a result, it is possible to prevent a situation where the connection time is prolonged due to a collision.

  In particular, in the communication system according to the fourth embodiment, since the signature selected by the base station 100 is included in the paging message and transmitted to the mobile station 200, the base station 100 selects the existing signal using the existing signal. The signature can be transmitted to the mobile station 200.

  In the communication system according to the fourth embodiment, a case is shown in which the base station 100 selects a signature and notifies the mobile station 200 of this by using a paging message. However, the present invention is not limited to this, and can be changed as appropriate. For example, not only the signature but also the frequency band position of the random access channel may be selected and notified to the mobile station 200 by a paging message. In this case, it is possible to reduce the probability of collision during random access by selecting the frequency band position of the random access channel, so it is possible to cope with paging responses occurring simultaneously in more mobile stations. It becomes.

  In addition to the frequency band position of the random access channel, a time position may be selected and notified to the mobile station by a paging message. In this case, since it is possible to further reduce the probability of collision at the time of random access, it becomes possible to cope with paging responses that have occurred simultaneously in more mobile stations.

  Further, in the communication system according to the fourth embodiment, as shown in FIG. 7, the base station management signature is described separately for handover and for paging response for the purpose of use. However, in the base station management signature, since the base station 100 already knows the purpose of the random access of the mobile station 200, it is not always necessary to distinguish between purposes. In particular, in the sense of expanding the options for base station management signatures, it is preferable not to distinguish these by purpose.

(Fifth embodiment)
In the communication systems according to the first to fourth embodiments, the case where the base station management signature range and the mobile station management signature range are fixed is shown. On the other hand, in the communication system according to the fifth embodiment, the respective ranges of the base station management signature and the mobile station management signature can be selected according to the situation of the base station 100. The communication system according to the fourth to fourth embodiments is different.

  FIG. 9 is a diagram for explaining an outline of signature setting in the communication system according to the fifth embodiment of the present invention. In the communication system according to the fifth embodiment, as shown in FIG. 9, when the number of mobile stations 200 communicating with the base station 100 is large, random access due to handover or the like is considered to increase. Increase station management signatures. On the other hand, when the number of mobile stations 200 communicating with the base station 100 is small, random access due to handover or the like is considered to be small. Therefore, in order to reduce the collision from the mobile station, the base station management signature is reduced, Increase mobile station management signatures.

  A signature setting example in the communication system according to the fifth embodiment will be specifically described below. FIG. 10 is a diagram showing a table (hereinafter referred to as “signature number determination table”) referred to when determining the number of base station management and mobile station management signatures in the communication system according to the fifth embodiment. is there. FIG. 11 is a diagram for explaining a signature setting example in the communication system according to the fifth embodiment.

  As shown in FIG. 10, in the signature number determination table, the number of mobile stations 200 with which the base station 100 is communicating (hereinafter referred to as “number of connected mobile stations”), the signature group management number, and the base station management The number of signatures is associated with the number of signatures for mobile station management. FIG. 10 shows a case where the thresholds for the number of connected mobile stations are four for A, B, C, and D (A <B <C <D). The base station 100 changes the number of base station management signatures and the number of mobile station management signatures by determining the signature group management number according to the number of connected mobile stations. A common signature is used between the base station 100 and the mobile station 200.

  FIG. 11A shows an example of setting a signature when the number of connected mobile stations is equal to or smaller than the smallest threshold A. FIG. 11A shows a case where signature group management number 1 is selected and there are more mobile station management signatures than base station management signatures. FIG. 11B shows an example of signature setting when the number of connected mobile stations is between the threshold B and the threshold C. FIG. 11B shows a case where signature group management number 3 is selected and the number of base station management signatures and the number of mobile station management signatures are the same. FIG. 11C shows an example of setting a signature when the number of connected mobile stations is equal to or greater than the largest threshold value D. FIG. 11C shows a case where the signature group management number 5 is selected and the mobile station management signature is smaller than the base station management signature.

  In the base station 100, a signature is selected from the signature group management numbers selected according to the number of connected mobile stations in this way. Then, the base station 100 notifies the mobile station 200 of the signature group management number through the broadcast information. Similar to the base station 100, the mobile station 200 selects a signature group corresponding to the signature group management number, and selects a signature from the selected signature group. Thus, since the broadcast information is included in the signature group management number, it is possible to notify the mobile station 200 of the signature group management number using existing signals.

  Here, a case is shown in which the number of signatures for base station management and mobile station management is changed according to the number of connected mobile stations. However, the index for changing the number of signatures for base station management and mobile station management is not limited to this, and can be changed as appropriate. For example, the usage rate of the downlink or uplink user data channel may be used as an index. In addition, it is preferable as an embodiment to consider the situation of adjacent base stations 100.

  Here, an example of the configuration of the base station 100 and the mobile station 200 included in the communication system according to the fifth embodiment will be described. FIG. 12 is a block diagram illustrating an example of a configuration of a base station included in the communication system according to the fifth embodiment. FIG. 13 is a block diagram illustrating an example of a configuration of a mobile station included in the communication system according to the fifth embodiment. 12 and 13, the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals, and the description thereof is omitted.

  The base station 100 included in the communication system according to the fifth embodiment relates to the first embodiment in that it has a signature group selection unit 1201 and that the signature selection unit 1202 and the signature management unit 1203 have different functions. Different from the base station 100. Hereinafter, the signature group selection unit 1201, the signature selection unit 1202, and the signature management unit 1203 will be described.

  The signature group selection unit 1201 selects a base station management signature group and a mobile station management signature group based on connection information with the mobile station 200 from an upper layer, and selects the selection result as a signature selection unit 1202 and The signature management unit 1203 is notified. In addition, the selected signature group management number is sent to the data control unit 101 in order to notify the mobile station 200 of information on the selected signature group with broadcast information. The signature selection unit selects a signature from the base station management signature group notified from the signature group selection unit and notifies the higher layer.

  The signature selection unit 1202 selects a signature from the base station management signature group notified from the signature group selection unit 1201 according to an instruction from the upper layer, and notifies the higher layer and signature management unit 1203 of the signature. When selecting a signature, the signature number used with respect to the signature management unit 1203 is confirmed, and the signature number used is excluded from the used signatures.

  Signature management section 1203 stores the signature number selected by signature selection section 1202 and deletes the base station management signature detected by preamble detection section 108 from the stored contents.

  On the other hand, the mobile station 200 included in the communication system according to the fifth embodiment is the first implementation in that the control data extraction unit 1301 and the signature selection unit 1302 have different functions and the signature group management unit 1303. It differs from the mobile station 200 which concerns on a form. Hereinafter, the control data extraction unit 1301, the signature selection unit 1302, and the signature group management unit 1303 will be described.

  The control data extraction unit 1301 separates received data into user data and control data. Scheduling information in the separated control data is passed to the scheduling unit 203, uplink synchronization information is passed to the synchronization correction unit 206, signature group management number is passed to the signature group management unit 1303, and other control data and user data To the upper layer. The signature group management unit 1303 constructs a signature group from the signature group management number received from the control data extraction unit 1301, and passes the signature group to the signature selection unit 1302.

  The signature selection unit 1302 selects a signature number to be used for random access according to an instruction from an upper layer. The purpose of random access is notified as an instruction from the upper layer. When the purpose of notification is the purpose of base station management such as handover or paging, the signature number instructed by the upper layer is selected, and when it is the purpose of mobile station management, the signature group management unit In accordance with the purpose, the signature group randomly selected from the signatures classified by purpose according to the purpose, and the selected signature number is passed to the preamble generation unit 205.

  As described above, in the communication system according to the fifth embodiment, the respective ranges of the base station management signature and the mobile station management signature can be selected according to the situation of the base station 100. It is possible to efficiently prevent collisions in the base station 100 in random access by selecting the optimum number of base station management and mobile station management signatures according to the situation.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited thereto, and can be appropriately changed within a range in which the effect of the present invention is exhibited. Other modifications can be made as appropriate without departing from the scope of the object of the present invention.

  For example, in the above embodiment, as an example of the reason for random access associated with the base station management signature, the response at the time of handover and paging reception is shown. Is possible. For example, a reason for maintaining synchronization may be associated as the reason for the random access. In this case, synchronization can be maintained under the initiative of the base station 100.

It is a figure for demonstrating the example of a signature setting in the communication system which concerns on the 1st Embodiment of this invention. It is a block diagram which shows an example of a structure of the base station which the communication system which concerns on 1st Embodiment has. It is a block diagram which shows an example of a structure of the mobile station which the communication system which concerns on 1st Embodiment has. It is a sequence chart for demonstrating an example of the random access procedure at the time of handover execution in the communication system which concerns on 1st Embodiment. It is a figure for demonstrating the example of a signature setting in the communication system which concerns on the 2nd Embodiment of this invention. It is a sequence chart for demonstrating an example of the random access procedure at the time of handover execution in the communication system which concerns on the 3rd Embodiment of invention. It is a figure for demonstrating the example of a signature setting in the communication system which concerns on the 4th Embodiment of this invention. It is a sequence chart for demonstrating an example of the random access procedure at the time of paging reception in the communication system which concerns on 4th Embodiment. It is a figure for demonstrating the outline | summary of the setting of the signature in the communication system which concerns on the 5th Embodiment of this invention. It is a figure which shows the signature number determination table of base station management and mobile station management in the communication system which concerns on 5th Embodiment. It is a figure for demonstrating the example of a signature setting in the communication system which concerns on 5th Embodiment. It is a block diagram which shows an example of a structure of the base station which the communication system which concerns on 5th Embodiment has. It is a block diagram which shows an example of a structure of the mobile station which the communication system which concerns on 5th Embodiment has. It is a figure for demonstrating the structure of the uplink of EUTRA. It is a figure for demonstrating the random access channel of the uplink of E-UTRA. It is a figure for demonstrating the structural example of the conventional signature. It is a figure for demonstrating the structural example of the conventional signature. It is a sequence chart for demonstrating an example of the procedure of the conventional random access. It is a figure for demonstrating arrangement | positioning of the base station in which a handover generate | occur | produces. It is a sequence chart for demonstrating an example of the procedure of the random access at the time of the conventional handover execution.

Explanation of symbols

100 Base station equipment (base station)
DESCRIPTION OF SYMBOLS 101 Data control part 102 OFDM modulation part 103 Scheduling part 104 Radio | wireless part 105 Channel estimation part 106 DFT-S-OFDM demodulation part 107 Control data extraction part 108 Preamble detection part 109 Signature selection part 110 Signature management part 200 Mobile station apparatus (mobile station) )
201 Data control unit 202 DFT-S-OFDM modulation unit 203 Scheduling unit 204 Signature selection unit 205 Preamble generation unit 206 Synchronization correction unit 207 Radio unit 208 Channel estimation unit 209 OFDM demodulation unit 210 Control data extraction unit

Claims (4)

  In a processing device implemented in a mobile station that performs random access using one signature from a signature group composed of a predetermined number of signatures,
  The signature group is:
  A first signature group composed of signatures that the mobile station cannot select and a second signature group composed of signatures that the mobile station can select;
  The signature number that identifies each of the signatures included in the first signature group and the signature number that identifies each of the signatures included in the second signature group are arranged according to a predetermined rule,
  A processing apparatus for identifying a signature included in the second signature group using information acquired from a base station and capable of identifying the number of signatures included in the second signature group .   In claim 1,
  The signature number that identifies each of the signatures included in the first signature group is continuous, and the signature number that identifies each of the signatures included in the second signature group is continuous apparatus.   In claim 1 or claim 2,
  A processing apparatus that causes the mobile station to perform random access to the base station using a signature selected from the second signature group.   In any one of Claims 1-3,
  When the mobile station obtains information by which the base station can identify the signature selected from the first signature group, the mobile station uses the selected signature to perform random access to the base station. A processing apparatus that is executed by a station.

Images